材料期刊网

将同一批超细钨粉,分成两组进行配炭,一组不添加抑制剂,另一组添加一定量Cr3C2和VC,分别将两组样品分成若干小样,在真空和氢气气氛中,采用不同温度进行碳化,分析不同WC样品粉末性能,并将1 200℃碳化的WC样品制备成钴含量为8％的硬质合金,比较合金性能及金相组织的差异.实验结果表明:在氢气气氛下,钨粉更易于碳化,碳化速度更快,WC的结晶更完整;碳化阶段添加抑制剂会抑制WC晶粒的长粗,但也抑制了WC晶粒生长的完整性;提高碳化温度可以改善WC的结晶完整性,WC的粒度也会随温度的升高而增大.氢气气氛碳化的WC制备成合金后晶粒度比真空碳化的WC粗,合金晶粒的均匀性更好,异常长粗的晶粒少;在碳化阶段添加抑制剂可以更好的抑制合金晶粒的长粗,同时也抑制了WC粉末晶粒结晶的完整性,从而导致合金在液相烧结阶段晶粒的异常长粗.

The same batch of ultrafine tungsten powder was divided into two groups for carbon mixing.Inhibitors were not added into one group,and certain amounts of Cr3C2 and VC were added into the other group.Then the two groups of powders were divided into several samples respectively,which were carbonized in a carbide furnace under vacuum conditions and hydrogen atmosphere at different temperatures.The properties of different WC samples were analyzed,and cemented carbides with cobalt content of 8％ (mass fraction) were prepared by WC samples carbonized at 1 200 ℃.Microstructure and properties of different alloy samples were compared.The experimental results show that tungsten powder is easy to be carbonized and the carbonization rate is faster,and the crystallization of tungsten carbide is more perfect in the hydrogen atmosphere.Adding inhibitor in carbonization stage can inhibit the growth of tungsten carbide grains,but also suppress the integrity of the grain growth of tungsten carbide.Increasing the carbonization temperature can improve the crystal integrity of tungsten carbide,but the grain size of tungsten carbide will increase with the increase of temperature.The grain size of the alloy prepared by WC carbonized in hydrogen atmosphere is coarser than that of WC carbonized in vacuum atmosphere,but the grain uniformity is better,and the amount of abnormal growth grain is small.Adding inhibitors in the carbonization stage can better restrain the grain size of the alloy,but also restrain the integrity of the crystal of tungsten carbide powder,which leads to the abnormal grain growth of the alloy during liquid phase sintering.